Lisa! There are many online pharmacies that Online Medicines Seller Registry approves. This is the exact source https://www.nhs.uk/nhs-services/online-services/how-to-order-repeat-prescriptions-online/ that tells you everything about ordering repeat prescriptions online. Just follow these steps:
First of all, find an online pharmacy that has already been experienced and approved by legal authorities. Personally, I prefer this https://codapharmacy.co.uk/ Coda Pharmacy because they deliver free NHS prescriptions.
In the second step, you will have to get the approval of a GP. You can just enter your location code here https://www.nhs.uk/service-search/find-a-gp and will find several GPs to get approval.
By the way, NHS also recommends the following online pharmacies in this regard: